Interfacial Thermal Stress Analysis of Anisotropic Multi-Layered Electronic Packaging Structures

1999 ◽  
Vol 122 (1) ◽  
pp. 61-66 ◽  
Author(s):  
Weidong Xie ◽  
Suresh K. Sitaraman
Keyword(s):  
Deformation Theory ◽  
Thermal Stresses ◽  
High Stress ◽  
Free Edge ◽  
Layered Structures ◽  
Thermal Gradients ◽  
Electronic Packages ◽  
Element Analysis ◽  
Laminate Theory ◽  
Electronic Assemblies

The presence of dissimilar material systems and thermal gradients introduce thermal stresses in multi-layered electronic assemblies and packages during fabrication and operation. The high stress gradients near the free edge of bonding interfaces of such structures may cause cracking and delamination leading to the failure or malfunction of electronic assemblies and packages. A simple but accurate engineering approach for the calculation of interlaminar thermal stresses due to thermal mismatch in multi-layered structures is needed so that designers can determine interlaminar thermal stresses easily without much computational efforts. A few approaches based on the generalized deformation theory have been published but most of them are only suitable for structures with symmetric layers. For electronic packages and assemblies, unsymmetric layers are often used. An improved approach, Classical Laminate Theory-Edge Stress Shape (CLT-ESS), for prediction of interlaminar thermal stresses that can be applied to multi-layered structures with unsymmetric layers is presented. Comparisons are made with finite element analysis results and are found to be favorable. The proposed approach provides an efficient way for the calculation of interlaminar thermal stresses. [S1043-7398(00)00901-4]

The Thermoelastic Analysis of Chip-Substrate System

2004 ◽  
Vol 126 (3) ◽  
pp. 325-332 ◽  
Author(s):  
Linzhi Wu
Keyword(s):  
Temperature Field ◽  
Stress Concentration ◽  
Integrated Circuits ◽  
Thermal Stresses ◽  
Free Edge ◽  
Thermal Gradients ◽  
Substrate Structure ◽  
Thermal Stress Field ◽  
Electronic Assemblies ◽  
Free Edges

The presence of dissimilar material systems and thermal gradients introduces thermal stresses in multi-layered electronic assemblies and packages during fabrication and operation. The thermal stresses of the chip-substrate structure near free edges play an important role in determining the reliability of electronic packaging structures. Therefore, it is important to provide designers a good estimate of free edge stresses. According to the heat conduction mechanism of integrated circuits, the temperature field distribution in the chip and substrate is derived and solved when the chip works in a steady state. Taking the temperature field in the chip and substrate as the heat source, we solve the thermal stress field in the chip and substrate by using the technique of Fourier’s series expansion. The effects of geometric parameters of the chip and substrate on thermal stresses are analyzed. From the analysis of thermal stresses in the chip-substrate structure, it can be found that the stress concentration near free edges is more prominent. In the design of electronic packagings, the stress concentration near free edges which may cause cracking and delamination leading to the failure or malfunction of electronic assemblies and packages should be taken into account in details.

Thermal Stresses in Layered Electronic Assemblies

1997 ◽  
Vol 119 (2) ◽  
pp. 127-132 ◽  
Author(s):  
Z. Q. Jiang ◽  
Y. Huang ◽  
A. Chandra
Keyword(s):  
Finite Element ◽  
Thermal Stresses ◽  
Interfacial Shear Stress ◽  
Beam Theory ◽  
Accurate Method ◽  
Accurate Estimate ◽  
Electronic Packages ◽  
Package Design ◽  
Adhesive Layers ◽  
Electronic Assemblies

Thermal stresses in layered electronic assemblies are one of the causes of the mechanical failure of electronic packages. A simple but accurate method of estimating these thermal stresses is needed for the design of these packages. A simple approach based on beam theory exists, but it suffers from nonequilibrium of the peeling stress distribution. An improved method that overcomes this drawback is proposed here. For layered electronics with thin adhesives, simple analytical expressions are obtained for interfacial shear stress and peeling stress, as well as for other stress components. The finite element method is used to verify these solutions. It shows excellent agreement between the finite element results and these simple solutions, especially when the moduli of adhesive layers are significantly lower than the moduli of the other layers. This method provides an accurate estimate of thermal stresses for use in package design involving thin and compliant interface or adhesive layers.

Combined Moisture and Thermal Stresses Failure Mode in a PLCC

1989 ◽  
Vol 111 (4) ◽  
pp. 249-254 ◽  
Author(s):  
Y. Kornblum ◽  
J. C. Glaser
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Failure Mode ◽  
Material Properties ◽  
Thermal Stresses ◽  
High Stress ◽  
The Body ◽  
Free State ◽  
Element Analysis ◽  
Working Model

A finite element analysis has been conducted to provide a new explanation for PLCC cracking during soldering and develop a working model for the cracking phenomena. The model shows that cracking is due to strong moisture, temperature and material properties gradients that are developed in the body of the PLCC and that the moisture is not accumulated in a free state under the pad. Instead it is distributed in three distinct regions in the PLCC encapsulation. The results of this model indicate high stress at points where cracks were reported to occur.

Fatigue Failure Analysis Using the Theory of Critical Distance

2011 ◽  
Vol 462-463 ◽  
pp. 663-667 ◽  
Author(s):  
Ruslizam Daud ◽  
Ahmad Kamal Ariffin ◽  
Shahrum Abdullah ◽  
Al Emran Ismail
Keyword(s):  
Stress Concentration ◽  
Fatigue Failure ◽  
Notch Root ◽  
High Stress ◽  
Critical Distance ◽  
Future Research ◽  
Element Analysis ◽  
Linear Elastic ◽  
The Finite Element Analysis ◽  
Elastic Fracture

This paper explores the initial potential of theory of critical distance (TCD) which offers essential fatigue failure prediction in engineering components. The intention is to find the most appropriate TCD approach for a case of multiple stress concentration features in future research. The TCD is based on critical distance from notch root and represents the extension of linear elastic fracture mechanics (LEFM) principles. The approach is allowing possibilities for fatigue limit prediction based on localized stress concentration, which are characterized by high stress gradients. Using the finite element analysis (FEA) results and some data from literature, TCD applications is illustrated by a case study on engineering components in different geometrical notch radius. Further applications of TCD to various kinds of engineering problems are discussed.

scholarly journals Behavior of Offshore Pile in Calcareous Sand—Case Study

2021 ◽  
Vol 9 (8) ◽  
pp. 839
Author(s):  
Tarek N. Salem ◽  
Nadia M. Elkhawas ◽  
Ahmed M. Elnady
Keyword(s):  
Load Capacity ◽  
High Stress ◽  
Embedment Depth ◽  
Shear Stresses ◽  
Northern Coast ◽  
Compression Tests ◽  
Calcareous Sand ◽  
Element Analysis ◽  
Mixing Ratios

The erosion of limestone and calcarenite ridges that existed parallel to the Mediterranean shoreline forms the calcareous sand (CS) formation at the surface layer of Egypt's northern coast. The CS is often combined with broken shells which are considered geotechnically problematic due to their possible crushability and relatively high compressibility. In this research, CS samples collected from a site along the northern coast of Egypt are studied to better understand its behavior under normal and shear stresses. Reconstituted CS specimens with different ratios of broken shells (BS) are also investigated to study the effect of BS ratios on the soil mixture strength behavior. The strength is evaluated using laboratory direct-shear and one-dimensional compression tests (oedometer test). The CS specimens are not exposed to significant crushability even under relatively high-stress levels. In addition, a 3D finite element analysis (FEA) is presented in this paper to study the degradation offshore pile capacity in CS having different percentages of BS. The stress–strain results using oedometer tests are compared with a numerical model, and it gave identical matching for most cases. The effects of pile diameter and embedment depth parameters are then studied for the case study on the northern coast. Three different mixing ratios of CS and BS have been used, CS + 10% BS, CS + 30% BS, and CS + 50% BS, which resulted in a decrease of the ultimate vertical compression pile load capacity by 8.8%, 15%, and 16%, respectively.

Natural frequency analysis of a functionally graded rotor-bearing system with a slant crack subjected to thermal gradients

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Arnab Bose ◽  
Prabhakar Sathujoda ◽  
Giacomo Canale
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Power Law ◽  
Beam Theory ◽  
Functionally Graded ◽  
Thermal Gradients ◽  
Element Analysis ◽  
Rotor Bearing ◽  
Natural Frequency Analysis ◽  
Bearing System

Abstract The present work aims to analyze the natural and whirl frequencies of a slant-cracked functionally graded rotor-bearing system using finite element analysis for the flexural vibrations. The functionally graded shaft is modelled using two nodded beam elements formulated using the Timoshenko beam theory. The flexibility matrix of a slant-cracked functionally graded shaft element has been derived using fracture mechanics concepts, which is further used to develop the stiffness matrix of a cracked element. Material properties are temperature and position-dependent and graded in a radial direction following power-law gradation. A Python code has been developed to carry out the complete finite element analysis to determine the Eigenvalues and Eigenvectors of a slant-cracked rotor subjected to different thermal gradients. The analysis investigates and further reveals significant effect of the power-law index and thermal gradients on the local flexibility coefficients of slant-cracked element and whirl natural frequencies of the cracked functionally graded rotor system.

scholarly journals Mechanical Integrity Assessment of Two-Side Etched Type Printed Circuit Heat Exchanger with Additional Elliptical Channel

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4711
Author(s):  
Armanto P. Simanjuntak ◽  
Jae-Young Lee
Keyword(s):  
Heat Exchanger ◽  
Stress Intensity ◽  
Maximum Stress ◽  
High Stress ◽  
Element Analysis ◽  
Integrity Assessment ◽  
Printed Circuit ◽  
Mechanical Integrity ◽  
Finite Element Analysis Simulation ◽  
Maximum Stress Intensity

Printed circuit heat exchangers (PCHEs) are often subject to high pressure and temperature difference between the hot and cold channels which may cause a mechanical integrity problem. A conventional plate heat exchanger where the channel geometries are semi-circular and etched at one side of the stacked plate is a common design in the market. However, the sharp edge tip channel may cause high stress intensity. Double-faced type PCHE appears with the promising ability to reduce the stress intensity and stress concentration factor. Finite element analysis simulation has been conducted to observe the mechanical integrity of double-etched printed circuit heat exchanger design. The application of an additional ellipse upper channel helps the stress intensity decrease in the proposed PCHE channel. Five different cases were simulated in this study. The simulation shows that the stress intensity was reduced up to 24% with the increase in additional elliptical channel radius. Besides that, the horizontal offset channels configuration was also investigated in this study. Simulation results show that the maximum stress intensity of 2.5 mm offset configuration is 9% lower compared to the maximum stress intensity of 0 mm offset. This work proposed an additional elliptical upper channel with a 2.5 mm offset configuration as an optimum design.

Finite Element Analysis of Thermal Stresses in Circumferential Cast Clasps of Removable Partial Dentures

2007 ◽  
Vol 23 ◽  
pp. 229-232
Author(s):  
Liliana Sandu ◽  
Nicolae Faur ◽  
Cristina Bortun ◽  
Sorin Porojan
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Thermal Stresses ◽  
Element Analysis ◽  
3 Dimensional ◽  
Thermal Changes ◽  
The Finite Element Analysis ◽  
Dimensional Finite Element ◽  
Back Action ◽  
Aggressive Effect

Several studies evaluated the removable partial dentures by the finite element analysis, but none of them evaluated thermal stresses. The purpose of the study was to explore the influence of thermal oral changes induced by hot/cold liquids and food on the circumferential cast clasps of removable partial dentures. A 3-dimensional finite element method was used to explore the temperature distribution, thermal stress and the influence of thermal changes on stresses and displacements of circumferential clasps during functions. Thermal variations induce stresses in dental clasps, high temperatures having a more aggressive effect than lower one. Cold liquids and food induce high stresses in the retentive clasp arms while hot ones in the occlusal rests of the clasps and for the back action clasp also in the minor connector. The study suggests the importance of consFigureidering thermal variations for stress analyses of the cast clasps.

Three Turnaround Heat Treating Studies

2003 ◽  
Author(s):  
Jaan Taagepera ◽  
Marty Clift ◽  
D. Mike DeHart ◽  
Keneth Marden
Keyword(s):  
Heat Treatment ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Thermal Stress ◽  
Thermal Stresses ◽  
Heat Treating ◽  
Element Analysis ◽  
Stress Profiles ◽  
Insight Into

Three vessel modifications requiring heat treatment were analyzed prior to and during a planned turnaround at a refinery. One was a thick nozzle that required weld build up. This nozzle had been in hydrogen service and required bake-out to reduce the potential for cracking during the weld build up. Finite element analysis was used to study the thermal stresses involved in the bake-out. Another heat treatment studied was a PWHT of a nozzle replacement. The heat treatment band and temperature were varied with location in order to minimize cost and reduction in remaining strength of the vessel. Again, FEA was used to provide insight into the thermal stress profiles during heat treatment. The fmal heat treatment study was for inserting a new nozzle in a 1-1/4Cr-1/2Mo reactor. While this material would ordinarily require PWHT, the alteration was proposed to be installed without PWHT. Though accepted by the Jurisdiction, this nozzle installation was ultimately cancelled.

Sign in / Sign up

Export Citation Format

Share Document